A traditional metal antenna is relatively large in both weight and volume, and thus inflexible to design and manufacture and relatively poor in self-reconfigurability and adaptation, which severely restricts further the improvement of development and performances of radar and communication systems. Therefore, in recent years, research theories on broadband and miniaturization as well as reconfiguration and multiplexing of the antenna tend to be active day by day.
Under such background, researchers put forward a novel antenna concept, i.e., a plasma antenna, and such antenna is a radiofrequency antenna taking plasma as an electromagnetic radiation and guiding it to medium. An instant bandwidth of the plasma antenna can be changed by changing a plasma concentration and the plasma antenna has large dynamic range. Dynamic parameters such as frequency, beam width, power, gain and directivity of the antenna can be adjusted by changing resonance, impedance, density and so on of the plasma. In addition, in an unactivated state of the plasma antenna, a radar scattering section can be ignored, and the antenna is only activated in a short time of communication sending or receiving, and disguise performance of the antenna is improved. These properties, can be broadly applied to fields such as various scout, early warning, and confrontation radars, satellite-borne, onboard and missile antennas, microwave imaging, antennas, and high signal-to-noise microwave communication antennas, thereby greatly attracting attention of researchers at domestic and foreign and becoming a hot spot in the field of antenna research.
However, most current research is limited to a gaseous plasma antenna, and it is nearly blank in research on a solid-state plasma antenna. But the solid-state plasma generally exists in semiconductor devices and does not need to be wrapped by a dielectric tube like the gaseous plasma, and has better safety and stability. It is found after theoretical research that when a DC bias voltage is applied to a P-I-N diode, a DC current will form the solid-state plasma consisting of free carriers (electrons and holes) on the surface. Such plasma has metal-like characteristics, that is, a reflection action for electromagnetic waves, and the reflection characteristic is closely related to microwave transmission characteristics, concentration and distribution of the surface plasma.
Therefore, how to manufacture a P-I-N diode to apply into a reconfigurable loop antenna becomes very important.